When Will Smith’s gallivanting around an eerie post-plague Manhattan with his German shepherd (played incisively by Abbey and Kona), I Am Legend feels fresh and gripping. Exit dog, enter the videogame night-people, and the film slowly but surely tilts into silly. The two-DVD ”special edition” is a different sort of rip-off: The second disc is reserved for an alternate version whose three bonus scenes humanize the critters but could have easily fit on one disc. EXTRAS No commentaries, lame ”awesome animated comics,” making-of docs you have to go online to watch — it’s a B movie with C- packaging.